So as I've mentioned this cab is very tech savvy for it's time. It featured not one, not two, but three speakers for audio powered by a two channel amplifier. However, it was not stereo. It had two speakers at the top left and right running in series off one channel, and a third larger speaker at the bottom running off the other sort of acting like a subwoofer, though by today's standards it does not output much bass.
Anyway, an attempt was made to re-use the existing amplifier. I determined it was 12VDC powered, had simply two inputs and two outputs. I got it working, but it was scratchy and unreliable.
So I decided to make my own 3-channel amplifier using a bunch of TEA2025B chips I had previously bought for the Defender Arcade Cabinet (which I'll post about at some point).
The entire project took about 5 or 6 hours.
Anyway, an attempt was made to re-use the existing amplifier. I determined it was 12VDC powered, had simply two inputs and two outputs. I got it working, but it was scratchy and unreliable.
So I decided to make my own 3-channel amplifier using a bunch of TEA2025B chips I had previously bought for the Defender Arcade Cabinet (which I'll post about at some point).
The entire project took about 5 or 6 hours.
Her'es what I came up with. One chip (U1) is configured in bridged mode for extra umph for the "subwoofer". The other chip (U2) is configured in stereo. The input signal is combined and filtered a bit for the bridge input. It has a filter cap and an LED for fun on the board so you know it's on.
There's the PCB I came up with, already drilled. It has problems but works. Namely, somehow the main power supply filter cap ended up adjacent to U1 and backwards which I had to troubleshoot. I am new to PCB layout and the software.
A couple of Primus albums later and it's wired up.
And after a couple hours troubleshooting, it works and was mounted to the inside of the cabinet. I was able to re-use the existing cabinets connectors (though all were re-wired, since I had to re-wire the speakers). I put on a simple headphone jack for the inputs, which will be plugged into either the Raspberry Pi headphone jack, or the HDMI to VGA converter's audio out in the future.
Here's behind the Turbo marquee, where the speakers were wired in series for mono and now are wired separately for stereo. I will be upgrading these someday, with car speakers probably, as they can't handle much power.
And the "subwoofer".
And check it out! I'm getting pretty decent resolution with my PCB creations and on top of that, this is the first time I remembered to mirror the text before printing so that it actually turned out non-mirrored on the final product.